Process of making hydrocyanic acid and cyanid salt therefrom.



UNITED STATES Patented December 15, 1903.

PATENT OFFICE.

, JAMES HUGH PAUL, OF CHARLTON, ENGLAND.

SPECIFICATION forming part of Letters Patent No. 746,876, dated December1903.

Application filed February 24,1903. $erial No. 14:4,910. (N ospecimens.)

7 of caustic potash or of caustic soda is treated with hydrocyanic acidobtained from sulfocyanid of soda or ferrocyanid of potassium. Thesolution is then evaporated and concentrated in vacuo and the cyanid ofpotassium or of sodium obtained in a solid state. When working withsulfocyanid of soda, nitric acid is required, the process of manufactureis tedious and expensive and the yield is unsatisfactory. When workingwith ferrocyanid of potassium, only about half the available cyanogen isyielded, (as prussic acid,) the other half remaining as an insolubledouble ferrocyanid of potassium and iron. In order to decompose thisresidue, protracted boiling with strong acid is necessary, thistreatment entailing a loss of hydrocyanic acid, owing to decomposition.

According to my improved method of manufacture ferrocyanid of calcium orthe double salt of ferrocyanid of calcium and potassium is heated inconjunction with sulfuric acid of suitable strength, (between ten andthirty per cent.,) with the result that hydrocyanic acid is yielded andthe formation of the insoluble double ferrocyanid avoided. A solution ofcaustic potash or of caustic soda is treated with the hydrocyanic acidso. obtained, a solution of cyanid of potassium or of sodium resulting.

-Where the conditions admit of the process being carried out locallythatis to say, where the eyanid solution is required for use in thetreatment of auriferous and argentiferous ores or for other purposes-thesolution last referred to is ready for use; but where such conditions donot prevail the solution may be evaporated and concentrated, as beforedescribed, and the cyanid of potassium or of sodium obtained in a solidstate convenient for transport. v

What I claim as my invention, and desire to secure by Letters Patent, is

1. The herein-described process for the manufacture of hydrocyanic acidconsisting in heating ferrocyanid of calcium in conjunction withsulfuric acid, substantially as set forth.

2. The herein-described process for the manufacture of hydrocyanic acidand of cyanid salts therefrom consisting in heating ferrocyanid ofcalcium in conjunction with sulfuric acid, producing hydrocyanic acid,and treating a solution of a caustic alkali with the acid so obtained, asolution of cyanid of the alkali employed resulting.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

JAMES HUGH PAUL.

Witnesses:

VIVIAN ELKINGTON, H- E. WILLIAMS.

